1. Field of the Invention
The invention relates to a web-fed rotary printing machine with at least one printing unit having at least one printing assembly which contains, arranged one above the other, a forme cylinder and an impression cylinder.
2. Description of the Related Art
DE 195 34 651 A1 shows a printing assembly for a rotary printing machine for indirect printing. Four printing-assembly cylinders are arranged one above the other, the journal mountings of which are capable of being clamped in jaws which are mounted movably on side walls by means of slides. The cylinders are accessible on the end face through an orifice in the side wall after the jaws have been moved away. The cylinders can then be equipped with sleeves having a different outside diameter. This design involves a relatively complicated construction.
According to U.S. Pat. No. 6,085,650 printing-assembly cylinders are mounted in slides which are displaceable on columns. Here, in each case, two cylinders can be positioned in such a way that they co-operate in direct intaglio printing. The columns must have sturdy dimensioning in order to achieve high stability.
The brochure xe2x80x9cDicowebxe2x80x9d by MAN Roland Druckmaschinen AG, Augsburg, 2000, shows printing units of a web-fed rotary printing machine, in which printing-assembly cylinders of a double printing assembly for rubber-to-rubber offset printing are mounted on both sides in slides. The slides are displaceable on guides which are fastened in each case to opposite panels of an aperture in side walls.
The object of the invention is to provide a rotary printing machine for direct printing, in which the printing-assembly cylinders are guided in a stable manner by means of a cost-effective device.
According to the invention, each printing unit includes a pair of side walls, each side wall including an aperture flanked by a pair of mutually facing panels The forme cylinder is driven by its own drive motor, and at least one of the cylinders has both of its ends mounted in slides moveable on straight guide elements arranged on at least one panel of each aperture. By the printing-assembly cylinders being mounted on the panels of the apertures of the side walls, a direct vertical introduction of the supporting forces for the printing-assembly cylinders into the side walls in their longitudinal direction takes place. The support therefore has high rigidity and low vibration, this being a precondition for a good print quality. High forces can be applied. The device is simple in structural terms and can therefore be produced cost-effectively. Thus, for example, the guide elements can be implemented by means of commercially available straight guides. The printing units are also distinguished by a compact space-saving form of construction.
Thus, printing can be carried out selectively by the intaglio printing method or the flexographic printing method by means of one and the same printing machine, and the machine can be changed over in a simple way from one method to the other. Both printing methods may also be used simultaneously. The printing machine manufacturer can produce the machines for both methods identically from the same components, thus making cost-effective manufacture possible. The printing machines can also be produced with a variable format, that is to say they can be converted in a simple way to other formats, that is to say other diameters of the printing-assembly cylinders and cut-off lengths. Furthermore, the printing machine can be changed over quickly to various production variants.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.